Traditionally, medication cartridges have been used with pen-type injectors and are prevalently used worldwide on reusable or multi-dose devices for invasive delivery of medication. However, in typical pen-type injectors, a cartridge is simply inserted into a pen-type injector and used to provide an injection. The pen-type injector does not have any method of determining if the medication cartridge is properly inserted or what type of medication is contained in the medication cartridge. The user must manually check the cartridge for proper insertion and must be sure that the medication is the correct one. This is important, since improper insertion can result in damage to the pen-type injector or in the administration of an incorrect dosage of medication, which could result in injury or death. Also, the user must know what type of medication is being used, since there are often different dosing requirements for different concentrations of the same medication.
To overcome, the proper insertion of the medication cartridge in the pen-type injection, Novo Nordisk developed a plastic cap that mated with matching teeth on the pen-type injector. If the teeth on the plastic cap were not properly lined up and seated in the pen-type injector, the pen-type injector could not be assembled and used. However, this design suffered from several drawbacks, for example, the user could simply force the cartridge into the pen-type injector and force the pen-type injector together by deforming the plastic cap. In addition, the plastic cap could be easily removed.
To overcome the drawbacks concerning what type of medication was contained in the medication cartridge, information was printed on the exterior of the medication cartridge and was viewable through a clear portion on the pen-type injector. However, the user must still view the printing on the cartridge and understand the information presented by the printing.